Physics

CBSE Class 12

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Draw a plot showing the variation of (i) electric field (E) and (ii) electric potential (V) with distance r due to a point charge Q.

For a point charge Q,

Electric potential is inversely proportional to r and Electric field is inversely proportional to r^{2}.

Electric Potential |
Electric field |

The graph below shows us the variation of E and V with distance ‘r’.

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12.

Define self-inductance of a coil. Show that magnetic energy required to build up the current I in a coil of self-inductance L is given by

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13.

A metallic rod of ‘L’ length is rotated with angular frequency of ‘ ’ with one end hinged at the centre and the other end at the circumference of a circular metallic ring of radius L, about an axis passing through the centre and perpendicular to the plane of the ring. A constant and uniform magnetic field B parallel to the axis is present everywhere. Deduce the expression for the emf between the centre and the metallic ring.

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14.

The figure shows a series LCR circuit with L = 5.0 H, C = 80 mF, R = 40 W connected to a variable frequency 240V source. Calculate.

(i) The angular frequency of the source which drives the circuit at resonance.

(ii) The current at the resonating frequency.

(iii) The rms potential drop across the capacitor at resonance.

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15.

A rectangular loop of wire of size 4 cm × 10 cm carries a steady current of 2A. A straight long wire carrying 5A current is kept near the loop as shown.

If the loop and the wire are coplanar, find

(i) the torque acting on the loop and

(ii) the magnitude and direction of the force on the loop due to the current carrying wire.

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16.

Using Kirchhoff’s rules determine the value of unknown resistance R in the circuit so that no current flows through 4 resistance. Also find the potential difference between A and D.

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17.

Under what condition does a biconvex lens of glass having a certain refractive index act as a plane glass sheet when immersed in a liquid?

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19.

A ray of light, incident on an equilateral glass prism ( μ_{g} = √3 ) moves parallel to the base line of the prism inside it. Find the angle of incidence for this ray.

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Textbook Solutions | Additional Questions